The electrically insulative properties of thermally stable plastic materials multi-functionally houses and insulates the electrical components contained therein for electrical switching applications. The impact resistance of the plastic material facilitates mounting the movable components within the plastic enclosure without fear of damage caused by the violent arcs that occur when the switch contacts are connected and disconnected while carrying current. Suitable plastic materials for the switch enclosure are "Valox", a registered trademark of General Electric Company for polybutylene terepthalate and "Noryl", a trademark of General Electric Company for a modified polyphenylene oxide. One such molded plastic enclosure for electrical disconnect switches is described within U.S. patent application Ser. No. 811,716, filed Dec. 20, 1985, which Application is incorporated herein for reference purposes.
It is understood that electric arcs will form between a pair of electric contacts when the current through the contacts is interrupted and some arc chute means is required to cool and quench the electric arc. The larger the current during interruption, the more intense the arc and, hence, the larger the arc chute required. The duration of the arc is also related to the time involved in moving the electric contacts to a sufficient distance such that the arc voltage necessary to maintain the arc is greater than the available systems voltage.
An early attempt to rapidly make and break electrical connection between a pair of separable contacts is found in U.S. Pat. No. 4,233,482, wherein the movable contact carrier engages an over-center spring to rapidly accelerate the opening and closing forces applied during manual operation of the movable contact carrier. This Patent describes a single pair of separable contacts for each phase of the current and, hence, requires a single sizable arc chute configuration.
The electric switch arrangement of the instant arrangement uniquely employs a double ended Z-shaped contact blade mounted on a rotary contact carrier for connecting and disconnecting the contacts between a pair of contact blades on opposite sides of the Z-shaped contact blade. The blades comprise a U-shaped configuration wherein one leg of the U is shorter than the other to create an extended magnetic air gap. The reduction in electromagnetic forces acting upon the Z-shaped contact blade and the contact stabs is thereby reduced to promote rapid separation between the Z-shaped contact blades and the U-shaped contact stabs.